双Buffer使用问题

在服务器启动时，类BufferPaddingExecutor构造函数对lastSecond进行初始化赋值，之后不再采用系统时间尽心校准，进而避免了时钟回调问题。我不太理解为什么要采用双buffer设计，既然lastSecond是稳定的lastSecond.incrementAndGet()进行递增，在每秒内的sequence（默认seqBits为13）也可以在0和8191间递增，那么此时采用双Buffer的意义是什么呢？

Start with the BufferPaddingExecutor constructor and trace how lastSecond, lastSecond.incrementAndGet(), seqBits, and the double-buffer design are used during server startup and per-second sequence generation. Done would be a maintainer-confirmed explanation of the double-buffer rationale and a clear decision on whether any code change is required.

Written by the indexing model from the issue text.